Printer having force compensating platen



Dec. 31, 1968 J. o. SCHAEFER PRINTER HAVING FORCE COMPENSATING PLATEN Filed April 17, 1967 Sheet JOHN 0. SCHAEFER ATTORNEY.

Dec. 31, 1968 J. o. SCHAEFER 3,413,933

PRINTER HAVING FORCE COMPENSATING PLATE" Sheet Filed April 17, 1967 FIG. 3

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United States 3,418,933 PRINTER HAVING FORCE COMPENSATING PLATEN John 0. Schaefer, Lexington, Ky., assignor to International Business Machines Corporation, Armonk, N.Y., a corporation of New York Filed Apr. 17, 1967, Ser. No. 631,308 11 Claims. (Cl. 101274) ABSTRACT OF THE DISCLOSURE CROSS REFERENCE TO COPENDING APPLICATION Reference is made to US. Patent No. 3,366,213, issued Jan. 30, 1968, entitled Variable Stroke Mechanism for Printing Platen, filed by James A. Craft and John O. Schaefer, which pertains to certain subject matter disclosed herein.

DISCLOSURE OF THE INVENTION I have overcome problems inherent in any mechanism that is required to develop controlled reaction pressure for printing a wide range of effective character sizes and shapes.

Direct impression print composition has, for the most part, been limited to sophisticated typewriters which serve the bulk of composition requirements. It is inherently impossible, however, to directly print large headline size characters from a typewriter. The practical art has employed a number of alternatives to direct impression composition principally including photographic printing, handset galley type, and cutout pasteups from mass printed character sets.

Direct impression large character printers shown in the patent literature usually employ an impacting print mechanism. While prior patents disclose direct impression printers employing a roller for developing printing force, the roller constructions previously known have all proven unsatisfactory for headline quality character reproduction. A roller construction suitable for printing a large block character proves unsatisfactory for printing smaller characters or for printing small components of large characters such as serifs and swirls. In printing individual characters, the force requirements for varied character shapes and sizes are not averaged as in printing large groups or blocks of characters. The magnitude of force required for acceptably printing a broad area by an ordinary roller often is so great as to deform or destroy fine detail portions of the master character. Also, ink ribbons have some optimum range of pressure for best operation. While this tolerance range may be relatively large in the case of high quality ribbons, the variety of pressures presented by an ordinary roller attempting to print the full range of an adequate headline character set may well exceed the tolerance of the ribbon.

The pressure device of my invention preferably ematent O ploys a plurality of laterally narrow, flexible steel rings that are loosely rotatably supported on a common shaft such that the rings can resiliently collapse to individually develop an increment of printing pressure. A rigid backup roll rotatably forces all of the individual rings into engagement with paper and an ink ribbon against a raised character master. Only those individual rings which oppose a portion of the raised character master will 'be flexed to develop any reaction force at all; the remaining rings simply free wheel.

If a broad area is to be printed, a large number of rings will flex to each develop its own component of resilient force and an over-all adequate pressure will be generated. If a small character or a serif is to be printed, only one or two of the rings may be deflected with the resultant small total force as required to print on the small area.

I have found that the hard surface of the steel rings provides more uniform print color than soft surfaces such as rubber.

I have discovered that my preferred roller construction is tolerant to minor variations in the surface height of the raised character masters. This tolerance is important as it reduces the manufacturing tolerances required for character masters and thereby reduces their manufacturing cost. Since printing force is a function of ring deflection, a variation in surface height will cause a variation in reaction force that potentially could cause non-uniform printing. The individual steel rings-of my preferred roller tend to flatten or ovalize when deflected, thus increasing the contact area somewhat in proportion with increased force. Within a range of deflections, the increase in area tends to compensate adequately for the force variation to maintain a substantially constant printing pressure (force divided by area).

My invention also includes means by which printing pressure can be varied to compensate for diiferent ribbon characteristics or widely different character sizes. This is accomplished by adjusting the relative position of the character master and the backup roll so as to vary the amount of ring deflection beyond the self-compensating range described above.

These and other objects, features and advantages of my invention will be apparent to those skilled in the art upon reading the following description of a specific preferred embodiment of my invention wherein reference is made to the accompanying drawings of which:

FIGURE 1 is a perspective over-all view of a headline printer of the type using a pressure roll assembly constructed in accordance with my invention;

FIGURE 2 is an exploded perspective view showing a preferred embodiment of my pressure roll assembly together with adjuvant mechanism cooperable therewith for performing many of the functions required for a complete headline printer;

FIGURE .3 is a fragmentary perspective view of the pressure roll assembly shown in FIGURE 2 more clearly showing the details of its construction;

FIGURE 4 is a partial front elevational cross-sectional view of the pressure roll assembly shown in FIGURES 2 and 3, illustrating its cooperative engagement with a typical character master and is taken along line IVIV of FIGURE 5;

FIGURE 5 is a partial side elevational cross-sectional view of the pressure roll assembly shown in FIGURE 4 and is taken along line V-V thereof;

FIGURE 6 shows several actual samples of characters that have been printed by my pressure roll; and

FIGURE 7 shows an alternate embodiment of my invention.

Referring now more specifically to FIGURE 1, there is shown a pressure transfer headline printer having a unitary character matrix or disk 11 that is rotatably mounted by a hub 12 to permit the operator to selectively position individual, downwardly facing raised or relieved surface character masters or symbols 11a on its undersurface at a printing position 13. Imaging media including a paper strip, web, or other record 14 is fed from an internal roll (not shown) past the printing position 13. The imaging media also preferably includes a pressure transfer ink ribbon 15 fed from an internal supply (not shown) between the matrix disk 11 and the paper 14, to an internal ribbon takeup. In the preferred embodiment shown, the ribbon 15 is fed at right angles to the paper 14. Best results have been obtained through the use of ink ribbons of the type disclosed in US. patent application Ser. No. 536,557 entitled, Transfer Medium and Method for Ma-king Same, filed Mar. 9, 1966, by H. T. Findlay and K. H. Froman.

Printing is controlled by depression of print key 16 and is preferably accompanied by automatic paper and ribbon feeding in proportion to the size of the character printed. In addition, several ancillary controls are provided including a paper feed expand-contract control 17, an impression control 18, and a print stroke cycle control 19.

A character size compensating pressure roll assembly or pressure means 20, constructed in accordance with my invention, is shown in its relation to other components of the printer 10 in FIGURE 2 and in greater detail in FIGURES 3 through 5. The roll assembly 20 includes a plurality of individually radially flexible cylindrical rings 21 that provide resiliently yieldably presented, hard surface portions 21a. The surface portions 21a are preferably hard to minimize surface embedding of the symbols 11a. I have found that embedding tends to undesirably concentrate force and ink density around the symbol periphery. The rings 21 are relatively narrow, i.e. short in the lateral or axial direction, and are loosely rotatably retained on a common elongated support shaft 22 and in close adjacency by a pair of set screw collars 23 to present a substantially laterally continuous roller or platen. The rings 21 are preferably made of Maraging steel, 300 grade so that they can be hardened by aging after forming without significant distortion. In a preferred embodiment of my invention, I have employed rings 21 having a wall thickness of .012 inch, a lateral width of .050 inch, an internal diameter 24 of 0.226 inch and a retaining shaft outside diameter 25 of 0.216 inch. As best shown in FIG- URE 3, a substantial clearance of approximately .010 inch exists between the inside of the ring 21 and the outside of the retaining shaft 22.

Force for printing pressure is generated as a flexural reaction in individual rings 21 which are urged into resilient cooperative engagement with the imaging media 14 and 15 and a selected character master 11a by a relatively large substantially rigid, rotatable backup roll 26, rotatably engaging the rings 21 on the opposed side thereof. Both shaft 22 and backup roll 26 are mounted in a frame or cage 27. The backup roll 26 in turn is rollably supported on a pair of eccentric rails 31 that extend the length of the longest required printing stroke. The eccentric rails 31 are rotatably mounted in a reciprocal support bracket 32 which is stationary during printing. Rails 31 are adjustable in unison (see FIGURE 2) by suitable control link age 33 to vary the vertical position of the backup roll 26 for impression control. The roller assembly 20 is caused to traverse the rails 31 and move across a selected character 11a by oscillatable print stroke drive bracket 34 which engages the assembly 20 by pin and slot connections 35.

Referring now more specifically to FIGURES 4 and 5, there is shown substantially the entire print force generat ing mechanism. Starting from the bottom of these figures, there is shown the essentially stationarily supported eccentric rails 31 on which backup roll 26 travels. The rings 21 which oppose a projecting part of the raised character 4 master 11a are in force engagement with the backup roll 26 and with the back side of paper '14. Ink ribbon 15 is positioned between the paper 14 and the raised character master 11a of the matrix 11. The matrix 11 is in turn supported vertically by frame mounted arms 41 which are also shown in FIGURE 2.

From FIGURE 4 it can be seen that all of the force transferred through the imaging media (paper 14 and ribbon 15) to the raised character master 11a can be observed in the flattening or ovalization of the ring 21. By rotating eccentric rails 31 to raise the roll assembly 20, a greater deflection can be generated in the rings 21 to increase the printing force.

FIGURE 5 is greatly exaggerated to show the effect of the individuality of the rings 21. Note that the character master 11a includes narrow, small area portions as well as relatively broad portions. It is seen that those rings 21 engaging any part of the raised character master 11a will be deflected and develop printing force whereas no force will be developed by the rings 21 which are not opposing any portion of the character master 11a. Accordingly, the broad areas receive greater over-all force than the narrow areas, since a greater number of rings 21 are deflected thereby.

Returning now to FIGURE 4, it will be seen that ovalization of a ring 21 tends to flatten it and increase its contact area with the paper 14. It also can be appreciated that any variation in the vertical or surface height of the character master 11a will result in a different degree of deflection of the rings 21 thus varying the force generated therein. Variations in surface height can occur either through the usual tolerance variations in manufacturing processes or due to continued wear or mistreatment of the character matrix 11. As explained above, the printing mechanism is quite tolerant of variations in surface height since flattening of the ring 21 due to increased force imposed thereby is somewhat balanced by increased contact area thus tending to maintain a substantially constant pressure (force divided by area), within a range of about .003 inch.

FIGURE 6 shows three typical characters actually printed by my pressure roll assembly in mechanism substantially as shown herein. Sample character 41 is a 60 point serif, sample 42 is a 14 point serif, and sample 43 is a 60 point script. The drawing attached hereto is a photolithographic reproduction of the original printing of these characters.

An understanding of the operation of the pressure roll assembly 20 can be had by further reference to FIGURE 2. Depression of print key 16 pivots clutch control link 51 clockwise against spring 52 to release clutch latch 54 which is retracted by spring 55 to release spring clutch 56. When released, spring clutch 56 connects worm gear sleeve 61 with coaxial, continuously running motor shaft 57 and, through helical gear 62, commences rotation of cam shaft 63.

It will be noted that cam shaft 63 supports three pairs of control cams 64-65, 66-67, and 68-69. The cams in each pair are alternatively cooperative with their respective cam followers as selected by the position of cycle control lever 19. In the position shown, single lobe or full revolution earns 65, 67, and 69 are effective. Helical gear 62 does not shift axially with cam shaft 63, but remains stationary as permitted by a key and slot connection 62a. The operation of the various cams is more completely described in aforesaid US. Patent No. 3,366,213.

Cam 67 is the first to be effective and moves follower 71 counterclockwise to pull link 72 and drive toggle linkage 73 over center to lift the print assembly 20 via the bracket 32 and rails 31 into printing position.

Next, cam 65 reaches a lift portion, and through follower 74 and linkage 75, drives stroke control arm 76 clockwise about its pivot shaft 36. Stroke drive bracket 34 is connected through pivoted latch link 37 to the stroke control arm 76 and follows the motion thereof. The pressure roll assembly 20 thus is caused to move to the right by the drive bracket 34 whereby it traverses the character master 11a to cause an ink transfer from the ribbon 15 onto the paper 14 as described above. At an appropriate time in the cycle after the stroke control arm 76 has completed its full stroke, cam 67 again becomes effective to move the pressure roll assembly downwardly through link 72 and the toggle linkage 73. All pressure is thus taken off the pressure roll assembly 20 so that paper and ribbon can be fed. The roll assembly is restored to the left by control arm 76 which acts against a tab 38 on drive bracket 34. After stroke control arm 76 has returned to its initial position, cycle clutch control cam 69 will be effective to pivot clutch restore bracket 58 counterclockwise whereby arm 59 thereof pivots cycle clutch latch 54 back into arresting position to intercept cycle clutch 56 and terminate the cycle.

FIGURE 7 shows roll assembly or pressure means 80 illustrating a further embodiment of my invention. Pressure means 80 includes a platen or roller composed of relatively rigid cylindrical members 81 that are loosely rotatably retained on a common elongated support shaft 82 and in close adjacency by set screw collars 83. Relatively hard surface portions 81a of the members 81 are individually resiliently yieldably presented for printing by a segmented backup roll 84 and leaf springs 85. Backup roll 84 comprises a plurality of separate disks or roll segments 86 each having a slotted bearing portion 87 that rotatably receives a corresponding leaf spring 85. A shaft 88 loosely rotatably retains the roll segments 86 in alignment with corresponding members 81. It will be appreciated that the pressure means 80 will develop only the force needed for printing a wide range of character sizes and shapes in much the same manner as pressure means 20 described above.

Those skilled in the art will recognize that I have invented a novel and imaginative pressure roller that is capable of producing high quality direct impression printed copy of a wide variety of character sizes and shapes. It also will be recognized that while my invention is directed to a small portion of the entire mechanism disclosed, that the value of this mechanism extends substantially to the entire machine which was not possible heretofore due to the inability to generate high quality printed characters. It is to be understood that the embodiment described herein is exemplary only and that many additions, deletions, substitutions and changes can be made without departing from the significant concepts of my invention as defined in the appended claims.

I claim:

1. A printer of the type wherein selectable, relieved surface symbols of varied configurations are transferred by pressure onto a record, and having a character size compensating roll assembly and means for moving the roll assembly across a selected symbol in pressure transfer cooperation therewith, said compensating roll assembly comprising:

an elongated support shaft,

means providing a plurality of relatively narrow, independently yieldably presented cylindrical surface portions assembled in a mutually continuous relationship on and rotatably supported by said support shaft to form a laterally continuous roller, said surface portions each being shorter in lateral extent than at least the larger varied configuration symbols transferrable by said printer, and

backup roll means rotatably engaging said roller for urging all of said cylindrical surface portions resiliently toward a selected symbol.

2. The improved pressure roll assembly defined in claim 1 wherein:

said surface portions are each provided by a flexible ring having an internal dimension that is sufficiently greater than the external dimension of said support shaft to permit deformation of said flexible ring and provide a pressure transfer contact surface that is compensatingly variable upon variation of force applied therethrough.

3. The improved pressure roll assembly defined in claim 2 wherein said backup roll is substantially rigid.

4. The improved pressure roll assembly defined in claim 1 wherein said surface portions are relatively hard.

5. A pressure transfer printer having means providing imaging media at a .printing position, a relieved surface symbol supported to face toward the media, pressure means for creating reaction force between the symbol and the media, and means for moving the pressure means across the symbol in pressure transfer cooperation therewith, said pressure means having a plurality of individually, resiliently, yieldably presented surface portions, means supporting said surface portions adjacent said imaging media, each of said surface portions having a short lateral extent relative to said symbol, and all of said surface portions being assembled in a mutually contiguous relationship to form a substantially laterally continuous platen for contacting the media.

6. The printer defined in claim 5 wherein each of said surface portions is provided by a rotatable cylinder and said rotatable cylinders are assembled to form a roller.

7. The printer defined in claim 6 wherein:

each of said cylinders is provided by a flexible ring,

said support means comprises a common support shaft upon which said rings are assembled, said shaft having an external dimension sufficiently less than the internal dimension of said rings to permit deformation of said flexible rings and provide a pressure transfer contact surface that is compensatingly variable upon variation of force applied therethrough, and

said roller is urged into contact with the media by a rigid backup roll.

8. The printer defined in claim '5 wherein said surface portions are relatively hard.

9. The printer defined in claim 5 wherein said imaging media includes a pressure transfer ink ribbon.

10. The printer defined in claim 5 wherein a unitary matrix carries a plurality of said symbols and is movable to permit individual selection of one of said plurality for printing.

11. The printer defined in claim 7 further comprising means for adjustably moving said backup roll toward and away from the symbol to vary the reaction force created.

References Cited UNITED STATES PATENTS 1,357,090 10/1920 Hasbrouck 197--6.4 2,804,968 9/1957 Elliott et al 10l--376 XR 2,888,873 6/1959 Uhl et al 101274 XR 2,942,544 6/1960 Williams 101269 3,277,991 10/1966 Weber et al 1976.4

ROBERT E. PULFREY, Primary Examiner.

E. S. BURR, Assistant Examiner.

US. Cl. X.R. 

